The term “one piece shower stall” unit is a misnomer. Actually, there are four parts to the basic shower unit. A base or drain pan unit, and one wall. Installing a one-piece shower can be very simple, if everything fits. It may also require some major remodeling efforts if the shower units do not fit the space in the home.
Installing a one piece shower stall, one accurately measures the space where the shower will be placed. Remove walls as necessary and build new walls to fit the size of the shower elected. This is only necessary if the space does not match the showers available.